This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A073062 #8 Mar 30 2012 17:26:02
%S A073062 2,23,571,2357,11131,711131,1923293,35711131,711131719,4753596167,
%T A073062 23571113171,379838997101,7535961677173,29313741434753,
%U A073062 571113171923293,7414347535961677,57111317192329313,167717379838997101
%N A073062 Take A000040, omit commas: 235711131719232931374143,... select first n-digit prime.
%e A073062 In the sequence 235711131719232931... (primes without delimiters) first 1-digit, 3-digit and 6-digit primes are 2,571,711131.
%t A073062 p200=Flatten[IntegerDigits[Prime[Range[200]]]]; pn := Partition[p200, n, 1]; ln=Length[pn]; tab := Table[Sum[10^(n-k)*pn[[i, k]], {k, n}], {i, ln}]; Do[Print[{n, Select[tab, PrimeQ][[1]]}], {n, 20}]
%K A073062 easy,nonn,base
%O A073062 1,1
%A A073062 _Zak Seidov_, Aug 22 2002